This invention relates to plastic containers and more particularly to a plastic container molded in one piece so as to include a drain back spout as molded.
In dispensing liquid from containers wherein only a portion of the contents of the container is used at any one time, as is the case with many products such as liquid detergents and bleaches, the consumer is concerned with the messiness which occurs from drops of the liquid contents draining down the neck and side of the container upon completion of the pouring. Thus, when a bottle having an upper neck is turned from its normal upright storage position to an inverted dispensing position and then back to its upright position, a few drops of such liquid will invariably drain down the outside of the neck of the container. A number of prior art container designs have disclosed various drain back spout (DBS) features for capturing such excess fluid and causing it to drain back into the container rather than drip down the neck and side.
Many of such DBS designs require a multiplicity of pieces which are assembled in a post molding operation, or require a re-shaping operation to re-position the spout. The self-draining containers of U.S. Pat. Nos. 4,989,757 and 5,114,659 overcame such problems encountered with multiple part self-draining containers by providing a one-piece self-draining container and method and apparatus for making the same so that the container can be molded in a single machine while incorporating a drain back spout feature as an integral part of the container, i.e., as part of the finish formed during the container molding operation. Thus, the only other element required for a complete package is a suitable removable closure for sealing the container. Such one-piece containers are much more economical to produce than a container requiring multiple pieces because the container is completed upon molding and hence post-molding operations are not required.
In the various embodiments of one-piece self-draining containers disclosed in the aforementioned ""757 patent, the dispensing spout is equal to or greater in diameter than the neck of the container, regardless of which of the methods and type of machine is employed in making the same. One such ""757 patent container is made by a type of blow molding characterized as injection-extrusion blow molding utilizing a blow molding machine of the type disclosed in U.S. Pat. No. 2,804,654 (hereinafter xe2x80x9c""654 machinexe2x80x9d) which is in widespread use by the assignee of the present invention. When so utilizing the ""654 machine to make the container of the ""757 patent, the lower or container-interior-facing-surface of the web member extends radially outwardly from the neck of the narrow-shouldered container body and at right angles to the axis A of the neck, whereas the upper interior surface of the web is slightly inclined in order to promote some limited liquid drainage back to the lowermost portion of the gap in the spout when the container is returned to its upright storage position.
The self-draining container of U.S. Pat. No. 5,114,659 is likewise made by a method performed by the ""654 machine in order to produce a one-piece self-draining container. However, the ""659 patent container differs in configuration from that of the ""757 patent in that the pour spout is smaller in diameter than the neck of the container and hence is better adapted to the broad shoulder type container body shown in the ""659 patent and hence is preferred for many applications.
In addition, the ""659 patent discloses a method of molding which provides internal threads with superior thread definition and lack of distortion by making the thread extend for at least two complete turns, i.e., 720xc2x0, so that at any axial section of the neck wall there will always be at least two thread segments. This overcame the problem of thread distortion when stripping of containers having a thread with less than two full turns that previously resulted in producing containers which, although functionally usable, were less than commercially desirable. This improved stripping action, as will be seen from the ""659 patent, was accomplished with a container neck of smaller diameter than the integral portion of the upper shoulder area of the container body to which the neck is joined, and also, of course, with a pour spout having a smaller diameter than that of the container neck.
However, in the one-piece self-draining container of the ""659 patent, like that of the container of FIG. 3 of the ""757 patent, the bottom or interior surface of the apron web extended radially in a plane perpendicular to the axis of the neck, and hence the upper surface of the web could only be sightly-inclined to thereby somewhat promote the aforementioned gravity drain back. The inclination of the web upper surface relative to the web lower surface is limited as a practical matter because excessive plastic thickness in the web negatively affects the mold cycle time and hence production efficiency. Such asymmetric cross-sectional shape of the web wall also produces some production problems, with respect to side loading of the tooling and tooling alignment.
Due to the foregoing limitations, the ledge formed by the web at the base of the pour spout is nearly flat. Hence with prior art DBS containers made in accordance with the ""659 patent for broad shouldered containers the spillage residue from the product dispensed from the container tends to remain inside the finish area. This remaining residual drain back product can result in a messy package for the consumer when pouring or re-applying the closure. Accordingly, there has existed a need for many years for improving DBS configuration in such one-piece plastic containers to better promote gravity drain back into the container without sacrificing the advantages of the method, apparatus and improved thread definition of the ""659 patent as practiced in ""654 machines and as applied to a broad-shoulder container body.
Accordingly, among the objects of the present invention are to provide a new and novel one-piece self-draining container which can be molded on a single machine, which requires no assembly operations, which has a steep inclination of the web drain wall that better promotes the product to drain away from the container finish back into the container, which enables the container drain web wall to be made of uniform plastic thickness and sufficiently thin so as not to negatively affect production cycle time.
Another object of the present invention is to provide an improved method and apparatus for making a container of the aforementioned character on a widely used ""654 type machine that is economically retrofitted in accordance with the invention with a minimum of component changes and modifications, that retains the advantages of the method and container of the ""659 patent, which eliminates the problems faced in the past with side loading of the tooling and tooling alignment concerns when fashioning the prior web of non-uniform thickness and non-parallel upper and lower surfaces, and that enables an improved container of the aforementioned character to be made in a rapid, reliable and economical manner with already available production equipment.
In general, and by way of summary description and not by way of limitation, the present invention accomplishes the foregoing objects by providing an improved one-piece self draining container and improved method and improved apparatus for forming the same. The container includes a body and a finish wall extending upwardly from a body opening. The finish wall surrounds a dispensing spout which extends above the top of the wall. A drain back apron web joins the finish wall and the dispensing spout and has a generally frustoconical contour to form a drain apron gutter channel having a relatively steeply inclined cone angle. A drain opening is defined adjacent the gutter channel, preferably in the form of a gap at the rear of the spout, for draining fluid from the channel into the container body. The apron web is preferably constructed and arranged to have generally parallel upper and lower wall surfaces sloping downwardly toward the spout in the container upright position.
The method of the invention for constructing the improved container is performed on a modified conventional ""654 type extrusion/injection blow molding machine that is operated in the conventional manner in a normal cycle so that the container is manufactured by a process in which at least the neck, dispensing spout, annular finish wall, apron web, and the drain gap through which liquids flow are formed in a first mold in one operation and the body is thereafter formed by blow molding, with no post-molding reconfiguring operations required for those portions formed in the first mold in order to provide the final as-molded container configuration. The conventional ""654 molding machine is modified by constructing and arranging the web forming portion of the injection mold cavity tooling to mold form a generally frustoconical upper surface on the web, and constructing and arranging the end surface of the extrusion die head that closes the injection mold cavity so as to mold form a generally frustoconical lower surface on the web. Preferably, this is accomplished by recessing the central surface on the mandrel end that mates with the lower end of the injection mold core pin so that these parts meet in a central abutment zone spaced below the annular extruder outlet formed between the upper end of the mandrel and the bushing that surrounds the mandrel in the extrusion tooling. A frustoconical surface is then formed on the mandrel end so as to encircle the recessed mandrel central surface and to taper upwardly and radially outwardly therefrom to intersect with the plane of the annular extrusion die outlet. Likewise the lower end of the finish insert sleeve of the injection mold tooling is reconfigured complemental to the mandrel end frustoconical surface so that the mold cavity surfaces define therebetween a mold cavity adapted to form the apron web such that it has a generally frustoconical contour.